Phototelegraph



Feb. 22, 19 27.

A. KORN PHQTOTELEGRAPH Filed m 5. 1923 4 Sheets-Sheet 1 A. KORNPHOTOTELEGRAPH Filed May 5. 1923 Feb. 22, 1927.

Feb. 22, 1927. 1,618,964

- A KORN PHOTOTBLEGRAPH mud in s. 1923 4 Sheets-Sheet s ch A. KORNruorommeana Filed M ay 5. 1923 4 Sheets-Sheet 4.

f at

Patented F b. 22,1927.

" new 1 ARTHUR noun, or cnmno'rrannonannan nnnnn't, GERMANY.

enorozrnnnemrn.

Application filed Kay 5, 1923, Serial No. 636,871, and in GermanyNovember 12,1921.

This invention refers to improvements in automatic phototelegraphs, andin particular to that kind of apparatus of thls kind which are providedwith photoelectric celIs 1n the 5 transmitter, and it is particularlyintended among other objects and advantages to 1ncrease'theadaptabllityof the so-called compensation method, and to generallymprove and perfect the arrangement, operation and 19 construction ofapparatus of this kind.

In my U. S.' Patent 888,098 I have described a method for considerablydiminish- 1 ing the errors glue to inertia, and occurring thetransmitters of phototelegraphic devices with selenium cells by using acombination of a feeler cell with a com ensation cell.

Besides the selenium cells re erred to there are, however, still otherphotoelectric cells the variations of resistance of which upon exposureto lightare considerably inferior to the changes of resistance ofselenium cells,

and of these I may mention the photoelectric cells according to Elster,Geitel and others by way of example. In accordance with my inventionmeans are provided for an improved arrangement of compensating meansmaking it possible, when applied notonly to selenium cells but also toany of the other weakly sensible photoelectric cells to pro ducesatisfactory and even'better results for larger distances than with thecompensation method heretofore known. In the same manner as seleniumcells every other photoelectric cells, that is to say, every compoundthe electric resistance of which is changed upon exposure to light, aswell as the corresponding pieces of apparatus for registering thesechanges and variations, exhibit a certain inertia, so that forinstancethe increment of current transmitted through a cell from aconstant battery, and registered by the device, and provided theirradiation at the time of commencement tzO shows the I increment AI isrepresented approximately by the formula t in which formula on, ,8, yare constants of erties of the registering devices; a isthesensitiveness the viz,

I t co zAi=aAI I ,8 is the constant of inertia proper. The

following ratio holding,

more the value of t is increased the slower I the value of A?! comesnearasymptotically to the value aAIZ'y in a great number of selenium cellsis equal to :3/2. Theproportionality of At, with 'AI holds true onlyapproximately, and the least in the vicinity of the zero irradiation. Inthe practice .of my invention in view of these facts in the vicinity ofthe zero irradiation a constant preliminary irradiation is imparted tothe photoelectric cells in phototelegraphic'trans mzssion, whereby theerror referred tofis obviate '5 In pursuance of the compensation methodotherwise known two photoelectric cells are exposed simultaneously tothe variations'of irradiation AI, and for the bridge current passingthrough the registerin device, a galvanometer for instance, and urnishedby a Wheatstone bridge formed by the cells and suitable resistances avalue of current is obtamed corresponding to the difference of the twochanges of resistance of the two .cells. Thus the-formula becomes i inwhich formula (1 ,8 are the two respective constants of one of thecells, ,3, are the two constants of the other cell. The constant y beassumed to be quickly as possible, so that dAt 727* resulting as thecondition for compensation in the values I I n ff zfiz o In view.,-,ofthe fact that a '1l should be 0 it follows that the sensitiveness ofiii) mission.

the, feeler cell should be greater and its inertia should be less thanthe corresponding values of the compensation cell.

The compensation method may be improved, provided the changes ofirradiation are received b the compensation c ll later than by the eelercell. This object may be accomplished by a suitable selection of thearrangement of the apparatus, or causing a small section of thetransparent field of irradiation to be exposed in such 'a manner thatthe retardation is produced by the movement of the picture carriers, sothat the field to be irradiated upon its passage I through the cone oflight is successively The invention will be more fully explained withreference to the accompanying drawings, showing by way of example and ina conventional way anexample of embody, ing the principles of myinvention. In the drawings Figure 1 illustrates diagrammatically therelative arrangement of the several pieces of apparatus and theirelectric connection. Figure 2 is an elevation of the transmitter, thesource of light being removed in conformity with line. 2-2 in Figure 3.In Figure 3 I have shown a sectional view on the line 34-3 of Figure 2,and Figure 4 is a section through the compensation cell on the line 44of Figure 5. Figure 5 is a section on the line 5-5 of Figure 4. InFigures 6 and 7 .different positions of the so-called chord galvanometerare shown in accordance with Figures 4 and 5. Figure 8 illustrates asectional view of the transmitter in accordance with Figure 2 butsomewhat modified, on the line 8-8 Figure 9, and Figure 9 is a sectionon the line 99 of Figure 8. -Fi re 10 is a section on the line 10-10 ofFigure 8. Figure 11 shows the icture carrier in elevation with two irraiation surfaces. Figures 12 and 13 are graphical representations of'theirradiation curves. Figure 14 illustrates diagrammaticall thearrangement of producing the retar ation by the movement of the picturecarrier.

In the transmission of pictures and the like by phototelegraphic meansthe film with the picture is placed upon a transparent glass cylinder 11which is mounted upon a and the plate 12.

18 a worm Wheel 22 is mounted which may 7 be driven by means of the worm23 of a motor engine 24. Upon the rotation of the worm wheel 2-2 thecasing 17 is rotated and carries the glass cylinder 11 along with it inits movement b means of the rollers 15 y thisineans the shaft 13 isrotated and screw threadedly ascends in the nut 14, so that the glasscylinder 11 is also moved u wards ina helical path.

Upon the ottom of the casing 21 the feeler cell 25 is mounted which mayeither comprise a selenium cell or any other suitable cell, thus forinstance a cell according to Elster and Geitel. Above-the feeler cell25" prism 26 adapted for total reflection is mounted sup orted upon apillar or the like 27. Upon t e casing 21 a tubular projection 28 with alens 29 is arranged in front of which a strong source of light ismounted comprising a shell 30, a lamp 31 and an adjustable condenserlens32. The shell 30 is provided with a threaded stud 33 guided in a support34, and capableof vertical adjustment by means of the nut 35. The lamp31 is adjusted in such, a manner by means of the nut 35 that it projectsits cone of light upon the lens 29 from which the pencil of rays isprojected u on a point on the pic ture carrier of the g ass cylinder 11.The light permeates the glass cylinder more or less in accordance withthe opaqueness of the picture carrier, and strikes the prism 26 fromwhich it is projected to the feeler cell 25.

a In accordance with the illustration in Figures 4v to 7 thecompensation cell 36 is mounted in a casing 37 which is preferablyclosed on top by glass rods 38. Above the casing 37 a prism 40 isprovided on a support 39 upon which, the light of the source of light isrojected comprising av shell or casing 41 with a lamp 42 mountedtherein,

and closed in front by an adjustable condenser lens 43. The casing 41 issupported .on the threaded stud 44 which by means of the nut 46 may beexactly adjusted in the vertical direction.

ed. This galvanometer comprises a base 47 upon which two coils 48 aremounted sur Bet-ween the lamp and the prism 40 a chord-galvanometer ismountthe" ole shoes through which the light'of the amp is adapted topass. The pole shoe confronting the prism 40 isprovided with a tube 51upon which a, lens53 may be displaced by means of the collars 52, saidlens 53 throwin the light of the lamp upon the prism which in its turnprojects the rays of light u on the compensation cell 36. Between t epole shoes 49 a frame 54 is arranged at one end of whicha rigidlysecured stud 55 with a roller 56 is mounted and adapted for connectionwith the conducting wire by means of the clamping screw 57. At

the other end of said frame 54 a stud 59 with roller 60 is adjustablysecured by means of thenut 58, and to which the other conducting wiremay be secured by means of the screw 61. The studs 55 and 59 arecarefully insulated in the frame 54 by means of the insulation 62, andover the rollers 56 and 60 an endless wire 63 is placed between the twosections of which a small foil 64 is mounted in such a manner that it issituated exactly within the pencil of rays emanating from the source oflight.

This wire is in electric connection with the circuit of the feelingcell, so that the movement of the foil or respectively of the wire 63 isgoverned by the change of current condition in the said feeling-circuitand the foil the change of current condition, and by controllinandregulating the passage of light from the source of light to thecompensating or wire 63 of the galvanometer on the sending andtransmitting station acts as akind of telegraph, the changing conditionof which is transmitted to a similar or equivalent member 81 at thereceiving station.

In accordance with Figure 7 the position of rest ofvthe foil 64 andof'the wire 63 are relatively arranged ,in such a manner that to a smallextent the light is already capable to penetrate to the compensationcell 36. This position is the extreme position preliminary irradiationof feeler cell is of interception so that a permanent weak irradiationof the cell will be secured.

This is the preliminary irradiation which 1s necessary for thesuccessful operation of the compensation cell. A permanent accomplishedin view of the fact that in the original films to be employed a certamtransparency exists also in the darkest sections of the picture; ifdesired, a preliminary irradiation of the feelercell may be v producedby a separate source of light, In

accordance. with the degree oftransparency of the picture carrier thewire 63 is capable of swinging more or less in conformity with thecurrent impulses admitted thereto, the

said wire being adapted for instance to oscillate around half of Figure6 or around the entire Figure 4, so as to permit the passe e IThe'device hereintofore described will opcrate as follows in accordancewith Figure 1: I

From a source of current, a battery 65 for instance the current passesthrough the conductor 66 to the compensation cell 36, and thence throu hthe conductor 67 to the feeler cell 25- whic is connected by theconductor 68 to the other terminal of the battery 65. Between the twoconductors 66 and 68 a connecting conductor 69' is shunted with aresistance 7 0 along which a contact'piece 71 is'adapted to slide whichis itself electrically connected by the conductor 72 with thereinforcer-tube arrangement 73 from which the conductor 74, 75 leads tothe conductor 67 intermediate the two photoelectric cells 25 and 36.The'conductor section from the contact piece 71 to the conductor 67constitutes the Wheatstone-bridge. A resistance 76 is shunted around thecompensation cell 36 and is connected at one end by means of theconductor 77 to the conductor 67, and over the conductor 77, while acontact piece '7 8 movable along the resistance 76 is connected to theconductor. 66 over the conduc- .tor 79. may thus be employed as a meansto indicate From the reinforcer lamps 73 thecon-ductor 80 passes to thereceiving apparatus, and to one terminal of the chord galvanometermounted at'81 of thesame construction as the galvanometer described withreference to Figures 4 to 7, and the other terminal of which isconnected to the return conductor 82 which leads back to the reinforcerlamps 73. The receiving means comprise a lightsensitivefilm wound upon adrum 83, and upon which the light of a lamp 84 is projected bythe lenses85 86. The receiving,

means are otherwise of the same construction as the transmitting andsending apparatus shown in Figures 2 and 3. Intermediate the lamp 84 andthe lens 86 the foil 87 of the galvanometer is situated the oscillationsof which expose areas of varying size of the admission openin for therays of light tothe light sensitive film upon the drum 83'.

At the transmitting station a conductor 88 is branched oil from theconductor 82 and leads to the frame of the alvanometer in accordancewith the illustration Figures 4 to .7. The other end of the chordgalvanometer I is connected by a conductor 89 to the resisttime .90along which a sliding contact piece 91 is ada'ptedto move which isconnected by means of the conductor 92 to the conductor 80.- The chordgalvanometer by means of its fo'il 64, regulate's'and controls theadmission of light from the lamp 42 to the comensation cell 36. In viewof the fact that e galvanometer for the compensation cell receives thecurrents which are reinforced V by the arrangement of reinforcing lampsthe oscillations of the galvanometer are considmation of the curve. LetM be the ordinate,

and t the abscissa. The two curves A6, and

At, represent the variations of the values of the resistance of the twocells and 36, and the curve of differences Ac extends between those twocurves in such a manner that it approaches asymptotically the value ofaAJ.

This action may be considerably im roved by causing the irradiation ofthe compensation cell to be accomplished somewhat in ar-- rear, that isto say, being for instance retarded for the value It, but then the morerapidly. In this case the several curves will assume the graphicalconfiguration in accordance with Figure 13, the curve of differencesshowing a rotruding hunch B at its commencement, an thereafter mergingthe more rapidly into the constant limit.

In the arrangement as shown in Figures 1 to 7 the retardation isproduced by the inertia of the system of irradiation of compensationcells, inasmuch as the transmission to the corresponding chordgalvanometer and the corresponding ieces of apparatus requires a certainperio of time.

The retardation may, however, also be effected in other ways; thus, forinstance by causing the irradiation-of the compensating cell 36 to beproduced by the same source of light, as employed for the feeler cell25, and preferably by permeating through the pic-- ture carrier.Inasmuchas these two cells should be arranged side by side of each otherthe same section of the picture carrier upon its movement through thepencil of rays of the irradiating lamp will project the amount ofirradiation proportionally corresponding to the feeler cell 25 upon thecompensation cell only with some retardation, whereby the desiredretarding action is produced.

1 Means for accomplishing this object are shown by way of example inFigures 8, 9, 10, 11 and 14 of the drawing. In this case the mechanicalportion of the transmitter is constructed so as to exactly correspond toFig ures 2 and 3, with the difference however that at the rear of thelens 29 a shutter 94 is mounted provided with a slot 95 elongated.

, tion. The rays of light penetratin through the slot 95 are not thrownin a body upon a cell, but they are distributed over the two cells 25and 36, so that the irradiated. portion of the picture carrier, so tospeak, is divided into two sections 96 and 97 (Figure 11). In view ofthe fact that the transparency of the picture carrier varies with thephotographic picture, and inasmuch as the section 9.6 replaces thesection 97 only upon continuing the rotation in the direction of thearrow 98, this action results in a retardation in the irradiation of thecompensation cell 36 which is governed exactly by the circumferentialvelocity of the picture carrier. 11. In this case the electricconnections should be changed somewhat, as shown in Figure 14' of thedrawing. .As shown in this figure the current passes fromthe battery 99and over the conductor 100 to the compensation cell 36, thence by way ofthe conductor 101 to the feeler cell 25, and back through conductor 102to the other terminal of the battery 99. Intermediate the two conductors100 and 102 the resistance 103 is shunted between which and theconductor 101 the VVheatstone-bridge is formed which consists of thecontact piece 104 movable and adjustable along the resistance 103, theconductor 105 which leads to the combination of reinforcing tubes 106,and the conductor 107 leading to the conductor 101. In parallel to thecompensation cell 36 the resistance 108 is arranged which is connectedby the conductor 109 to the conductor 101 and u on which a slidingcontact 110 is adapte over the conductor 111. From the reinforcmg tubes106 the two conductors 112 and 113 lead to the registering device 114 ofthe receiving station. I

As hereinbefore sumed that the current emanating from the reinforcingtubesor equivalent means are conducted directly to the receiving stationby conducting wires. It is obvious, however, that the currents may alsobe transmitted by wireless methods, without requiring any change in theprinciples and the systion of the picture at the receiving station. I

I also wish it to be understood that my invention is susceptible ofvarious embodiments other than those shown and hereinbefore described byway of example and for" convenience of illustration, the drawings beingmore or less conventional, and not be.- ing intended for limiting theinvention to any particular form and arrangement of to move which isitself connected to the conductor 100 set forth, it has been asparts,but various changes and modifications may occur to the expert to betteradapt the invention to varying conditions of application, and to theconvenience of the o orator, and without departing from the spirit andscope of the invention as expressed in the claims.

The invention may be employed-among other uses to]; the phototelegraphictransmission of pictures, manuscripts, and for other visual or opticalimpressions, and for similar purposes, and it may also be applied to thereproduction of pictures bymeans of changes of resistance produced todistant-- optically recording electric conductors, electricallyconnecting said optically responsive"v electric resistances withelectric compensating resistances, "adapted to compensate the lag ofresponsiveness in said optically sensitive resistances, and impartingadditional constant preliminary irradiation to said compensatingresistances.

2. In the art of photoelectrically transmitting pictorial and visualrepresentations,

changing the resistance of optically respon sive electric conductors byirradiation,

transmitting the changes of resistance .produced to distantopticallyrecording electric conductors, mounting optically responsiveelectric compensating resistances, ,adapted to compensate the lag ofresponsiveness in the electric conductors first mentioned in-therelative vicinity thereof, and imparting a constant preliminaryirradiation to said compensating resistances.

3. In the art of mitting pictorial an visual representations,

hotoelectrically transchanging the resistance of optically responsiveelectric conductors by irradiation,

transmitting the changes produced. to dis-' tant optically recordingelectric conductors,

, pensatin mounting optically responsive electric comg resistances,adapted to compensate the ag of responsiveness in the. electricconductors first mentioned in seriescon'nection and in relative vicinitytherewith, and

imparting a preliminary irradiation to said compensating resistances.

4. In the art of photoelectrically'transmitting pictorial and visualrepresentations and-ther tically responsive electric conductors by 1r'radiation, mounting compensating addityiom ike, changing the resistanceof op a1 similarly optically responsive ele ctric conductors in seriesand in relative vicinity of said first mentioned conductors, impartinga' preliminary irradiation to said compensatmg conductors, closing anelectriccircuit through said two kinds of conductors, arranging avariable bridge current in shunt on said circuit, and causing thevariations produced in said bridge current to be transmitted to distantmovable and optically recording electric conductors.

5. In the art of photoelectrically transmitting 'ictorial and visualrepresentations and the ike, changing the resistance of opticallyresponsive electric conductors by irradiations, compensating the lag 'ofresponsiveness of said conductors by mountmg compensating additionalsimilarly "optica ly responsive electric'conductors in ser es an mrelative vicinityf'of said first mentioned conductors, imparting aconstant preliminary irradiation to sand compensating conductors,.closing an electric. c1rcu1t through said two kinds "of honductors, ar-1 rangin a variable-bridge current 1n shunt on sai circuit, causing saidcurrent to pass through current reinforcing means, and transmitting thevariations produced in said bridge current to distant optically record:ing electric conductors.

visual representations and the hire, changinglthe resistance ofoptically responsive electric conductors by irradiations, compensatingthe lag of responsiveness of said conductors by mountin compensatingadditional similarly optica y re sponsive' electric conductors ofsmaller sensitiveness and greater coefficient of lnertia than said firstmentioned conductors in series therewith and in the relative vicinitthereof, closing an electric circuit throng said two kinds ofconductors, imparting a preliminaryirradiation to said compensat-' mgconductors, and transmitting the changes 1'10 and variations produced insaid circuit to distant. optically, registering and optically influencedelectric conductors.

7. In the art of hotoelectrically trans- 95 6.111 the art ofghotoelectrically trans mitting ictorial an mitting pictorial an visualrepresentations 5 I and the like, changin the resistance of o ticallyresponsive e ectrio conductors y irradiation com ensating the lag ofresponsiveness o sai conductors by mounting compensating additionalsimilarly optically 12o a responsive electric conductors of less sens1-'tiveness and greater ,coeflicientof inertia than said first mentionedconductors in series therewith and in' the relative vicinit thereof,closin an electric circuit throng said two kin s of conductors,imparting separate irradiation to the compensating conductors, arranginga variable bridge current in shunt on said circuit, causingsaid 7 bridgecurrent to pass current ne1n- 1 0 tant optically recording electricconductors.

forcing means, and transmitting the-variations produced in said bridgecurrent to dis- 8. In the art of (photoelectrically transmittingpictorial an visual representations I and the like, changingthe-resistance of optically responsive electric conductors byirradiation, compensating the lag of responsiveness of said conductorsby mounting compensating additional similarly optically responsiveelectric conductors'in series therewith and in the comparative vicinitythereoptically responsive electric conductors by irradiation,compensating the lag of rc-' sponsiveness of said con ctors by mount-1ng compensatlng electric similarly .optlcally responsive conductors 1nseries and in the 'com arative vicinity of said first mentioned conuctors, projecting light from a common source on sand two kinds ofconductors, and

' causing the compensating conductors to be retardedlyirradiated by saidlight, closing an electric circuit through said two kinds of conductors,arranging a bridge current on said circuit, passing said bridge currentthrough current reinforcing means, and transmitting the changes producedin said bridge current to distant optically sensitive recordingirradiated electric conductors."

10. Device for photoelectrically transmitting pictorial, visual or otherrepresentatlons, comprising a sending and transmitting station, and areceiving station, electric conducting means of optically controlledvarylng resistance at the sending station, and.

optically controlled varying compensating electric resistance means inseries with the other electricoptically controlled conductors at saidtransmitting station, and means to impart a constant retardation ofirradiation I at the transmitting station to oneof the electricopticallyresponsive conducting means, and irradiating means at bothstat1ons and current increasing valves intermediate the transmitting'andreceiving stations. 1

11. Device'for photoelectrically transmitting pictorial, visual andother representations, comprising a sending or transmitting station, anda receiving station, electric 'conducting means with opticallycontrolled varying resistance at the sendin station, compensating,similarly optical responsive electric conducting means at t e saidsending station and in series with the other optically responsiveconductors at said station, means adapted to produce aconstant-preliminary irradiation of said compensating conducting means,movable current-changeresponsive and indicating means, shunted on theconducting means of said sending ortransmitting station, and adapted totransmit the change of resistance to the receiving 'station, andirradiating means at both stations. '12. Device for photoelec ricallytransmitting pictorial, visual and other representations, comprising asending station and a receiving station, and conducting circuits forboth stations, electric conducting means with optically controlledvarying resistance at the sending station, com ensating, similarlyoptically responsive e ectric conducting means at the sending station'inseries with the other optically controlled resistance, avariable-resistance bridge circuit-shunted on the conducting circuit ofthe sending station, light-projecting means at both stations, agalvanometer at the sending station, inserted on said bridge circuit,and intermediate the light-projecting means and the optically responsiveconducting means,

reproducing means at the receiving station, and a message-recelvln'galvanometer 1n the conducting circuit 0 the receiving sta- 'tion andintermediate the light-projecting means and the reproducing means, andcurrent-reinforcing tubes on the galvanometercircuit.

13. Device for photoelectrically transmitting pictorial, visual andother representa; tions, comprising a sending station and a receivingstation,"an electric" circuit at each of said stations and opticallyinfluenced reproducing means at the receiving station, an opticallycontrolled electric conductor with,varyin resistance at thesendingstation include in the electric circuit theregf,

a source of light at each station and a d1s-" placeable picture carrierintermediate said conductor and said source of light at the sendingstation, a compensating, similarly optically responsive conductor withvarying resistance at the sending station, adapted to be influenced bythe source oflight and in series with the first-mentioned'conductor ofsaid station, a galvanometer at the sending station intermediate thesource of li ht and the compensating conductor, a bridge circuit,including said galvanometer and shunted off from the conductor circuit,a similar recording galvanometer at the receiving vstation, electricallyinfluenced by the first mentioned galvanometer and intermediate thesource of light and the reproducing means at said receiving station,currentreinforcing means on the galvanometer-circuit, and anoscillatable foil on each gal vanometer opposite the source of li ht,and a variable regulating resistance in t e sending galvanometercircuit.

14. Device for photoelectrically transmitting pictorial, visual andother representa circuits and in line with the optically controlledresistance of the sending station, picture-carriers in line with thesources of light and in line with the optically controlled conductor atthe sending station, a similarly optically infiuenceable compensatingconductor at the sending station in series Wlth'thG first-mentionedconductor and in the comparative vicinity thereof and opposite thesource of light, means associated with the picture carrier of thesending station for retarding the irradiation of said compensatingconductor, current-reinforcing means at said sending station, andmovable current change responding means shunted on said reinforcingmeans and intermediate the source of light and the compensating means,and electrically influenced, movable recording means at the receivingstat-ion intermediate the source of rier thereof. p

1 5. Device for photoelectrically transmitting pictorial, visual andother representations, comprising a sending station and a receivingstation, a source of light at eachstation, a movable picture-carrier ateach station opposite the source of light, electric conducting meanswith optically controlled varying resistance at the sending station inline with the picture carrier and adapted to be influenced by the sourceof light, a similar. optically influenceable compensating conductor atthe sending station in series with the first-mentioned conductor andopposite the source of light, means on said pictnre carrier forretarding and controlling the irradiation of said compensatingconductor, current-reinforcing meansat said sending station, andmovable, electrically influenced, light-controlling means shunted onsaid reinforcing means and intermediate the source of light and thecompensating means, electrically influenced similar light controllingand recording means at the receiving station intermediate the source oflight and the picture carrier thereof, and adapted to be influenced bythe light-controlling means at the sendingstation.

16. Device for photoelectrlcally transmitting pictorial, visual andother representalight and the picture-car tions, comprising a sendingstatipn-and a receiving station, a source of light at each statlon, amovable translucent picture car- 'rier at each station opposite the saidsource of light thereof, electric conducting means with opticallycontrolled varying resistan e at the sending station associated with t epicture-carrier and adapted to be influenced by the source of light, asimilar optically influenceable compensating conductor at the sendingstation in series with the first mentioned conductor and relativelyadjacent thereto and opposite the'source of light, a shutter at thesending station intermediate the source of light and the picture-carrierthereof, transversely slotted and codirectionally movable with relationto the picturecarrier and intersecting the path of light,

current-reinforcing means. on said sending station, and movablelight-controlling means shunted on said reinforcing means-andintermediate the source of light and the compensating' conductor,electric-ally influenced similar light-controlling and recording meansat the receiving station; intermediate the source of light andithepicture carrier thereof, and adapted to be influenced by thelight-controllingmeans at,the sending station.

17. In the photoelectric transmission of pictorial, visual and otherrepresentations, a sending station and a receiving station, electricconducting means with optically sensitive and responsive seriallyconnected resistances at the sending station, a movable picture carrierat each station, irradiating means on each station, telegraphictransmit+ ting means at the sendin station electrically influenced bythe optical y responsive resistances, and similar telegraphic means atthe receiving station adaptedto be influenced by the transmitting meansat the sending station and current reinforcing means -in connected tosaid optically responsive re;

sistances, correspondingrecording means at the other station and adaptedto be in- Y fluenced by the first mentioned movable light-controllingmeans, a picture carrier at the last'mentioned station in line with therecording means of said statlon, and means to "impart additionalirradiation to one of the said optically responsive resistances.

ARTHUR KORN.

